Strategies for Stabilization and Activation of Biocatalysts in Organic Solvents
Stepankova, V., Bidmanova, S., Koudelakova, T., Prokop, Z., Chaloupkova, R., Damborsky, J.
ACS CATALYSIS 3: 2823-2836 (2013)
One of the major barriers to the use of enzymes in industrial biotechnology is their insufficient stability under processing conditions. The use of organic solvent systems instead of aqueous media for enzymatic reactions offers numerous advantages, such as increased solubility of hydrophobic substrates or suppression of water-dependent side reactions. For example, reverse hydrolysis reactions that form esters from acids and alcohols can become thermodynamically favourable in organic solution. However, organic solvents often inactivate enzymes. Industry and academia have devoted considerable effort into developing effective strategies to enhance the lifetime of enzymes in the presence of organic solvents. The strategies can be grouped into three main categories: (i) isolation of novel enzymes functioning under extreme conditions, (ii) modification of enzyme structures to increase their resistance towards non-conventional media, and (iii) modification of the solvent environment to decrease its denaturing effect on enzymes. Here, we discuss successful examples representing each of these categories and summarize their advantages and disadvantages. Finally, we highlight some potential future research directions in the field, such as investigation of novel nanomaterials for immobilization, wider application of computational tools for semi-rational prediction of stabilizing mutations, knowledge-driven modification of key structural elements learned from successfully engineered proteins or replacement of volatile organic solvents by ionic liquids and deep eutectic solvents.